Molecularly imprinted polymer modified carbon fiber electrode, detection system comprising molecularly imprinted polymer modified carbon fiber electrode and application method of molecularly imprinted polymer modified carbon fiber electrode in tartaric acid detection

Abstract

The invention belongs to the technical field of food analysis and detection, and particularly discloses a method for rapidly detecting tartaric acid in wine based on a molecularly imprinted polymer (MIP) modified carbon fiber electrode. According to the method, a tartaric acid molecularly imprinted polymer layer is constructed on the surface of a carbon fiber electrode by adopting an electrochemical polymerization technology, and high-sensitivity and high-selectivity detection of tartaric acid is realized in a potential range of-0.5 to + 0.6 V (vs.Ag / AgCl) in combination with a differential pulse voltammetry (DPV). The modified electrode has excellent conductivity and specific recognition capability, the detection limit is as low as 0.05 [mu] mol / L, and the linear range is 1-800 [mu] mol / L. The method is simple and convenient to operate, the single detection only needs 20 seconds, the relative standard deviation is less than 3.5%, the recovery rate reaches 95-102%, the method can be directly applied to stock solution detection of complex wine matrixes (such as dry red wine, dry white wine and sweet wine), complex pretreatment is not needed, and an efficient and reliable analysis means is provided for wine brewing process monitoring and quality evaluation.

Description

Technical Field

[0001] This invention belongs to the field of food analysis and testing technology, specifically relating to a molecularly imprinted polymer-modified carbon fiber electrode, including its detection system and its application method in the detection of tartaric acid. Background Technology

[0002] The tartaric acid content in wine is a key indicator affecting its quality and stability. Traditional detection methods, such as ion chromatography (IC) and high-performance liquid chromatography (HPLC), rely on large instruments and involve complex pretreatment, while acid-base titration is susceptible to interference from other organic acids. Existing electrochemical sensors, although offering rapid response, suffer from poor selectivity. Molecular imprinting technology, by constructing specific recognition sites using template molecules, provides a new approach to solving the selectivity problem.

[0003] However, the insulating properties of traditional molecularly imprinted materials limit their application in electrochemical sensing. Summary of the Invention

[0004] This invention aims to provide a molecularly imprinted polymer-modified carbon fiber electrode, including its detection system and its application method in the detection of tartaric acid, as detailed below:

[0005] A molecularly imprinted polymer-modified carbon fiber electrode includes a carbon fiber substrate and a tartaric acid molecularly imprinted polymer layer formed on the surface of the carbon fiber substrate by electrochemical polymerization.

[0006] The carbon fiber substrate undergoes ultrasonic cleaning pretreatment with ethanol and water.

[0007] The molecularly imprinted polymer layer is formed by electrochemical polymerization using o-phenylenediamine as a functional monomer and tartaric acid as a template molecule.

[0008] After ultrasonic cleaning and pretreatment with ethanol and water, the carbon fiber substrate was dried. Using acetate buffer as solvent, tartaric acid and o-phenylenediamine were used as template molecules and functional monomers, respectively. The treated carbon fiber substrate was immersed in the above polymerization solution, and cyclic voltammetry was used to carry out 30 cycles of electropolymerization between 0 and +0.8V to form a molecularly imprinted polymer film on the surface of the carbon fiber substrate. Then, the carbon fiber electrode was eluted in an ethanol-water solution to remove the template molecules, thus obtaining the carbon fiber electrode modified with the molecularly imprinted polymer.

[0009] A method for applying a molecularly imprinted polymer-modified carbon fiber electrode in the detection of tartaric acid is characterized by comprising the following steps: placing the prepared carbon fiber electrode in a potassium ferricyanide solution for detection, and using differential pulse voltammetry to detect the characteristic oxidation peak of tartaric acid in the potential range of -0.5 to +0.6 V (vs. Ag / AgCl) to achieve quantitative analysis.

[0010] Using 0.1M PBS as the electrolyte, the detection limit was 0.05 μmol / L, and the linear range was 1-800 μmol / L.

[0011] The electrolyte has a pH of 3.5-6.5.

[0012] A molecularly imprinted polymer-modified carbon fiber electrode is applied to a rapid detection system for tartaric acid in wine.

[0013] The method described in this invention employs electrochemical polymerization to construct a tartaric acid molecularly imprinted polymer layer on the surface of a carbon fiber electrode. Combined with differential pulse voltammetry (DPV), it achieves high sensitivity and selectivity for tartaric acid detection within a potential range of -0.5 to +0.6 V (vs. Ag / AgCl). The modified electrode exhibits excellent conductivity and specific recognition capabilities, with a detection limit as low as 0.05 μmol / L and a linear range of 1-800 μmol / L. This method is simple to operate, requiring only 20 seconds for a single detection, with a relative standard deviation of <3.5% and a recovery rate of 98%-102%. It can be directly applied to the detection of raw materials in complex wine matrices (such as dry red, dry white, and sweet wines) without complex pretreatment, providing an efficient and reliable analytical tool for monitoring winemaking processes and evaluating quality.

[0014] This invention has the following innovative features:

[0015] 1. A tartaric acid molecularly imprinted polymer layer is constructed on the surface of a carbon fiber electrode using electrochemical polymerization technology, which has both high selectivity and high conductivity; moreover, the present invention has high selectivity for tartaric acid and can effectively eliminate the interference of organic acids such as citric acid and malic acid in wine.

[0016] 2. Optimize detection conditions by using differential pulse voltammetry (DPV) to adsorb tartaric acid in solutions of different concentrations, and then achieve rapid and high-sensitivity detection in potassium ferricyanide solution.

[0017] 3. The method is simple to operate, and a single detection takes only 20 seconds (relative standard deviation <3.5%, recovery rate 95%-102%). It is suitable for the direct detection of complex wine matrices / liquids (such as dry red, dry white, sweet wine, etc.) (no complicated pretreatment required). Attached Figure Description

[0018] Figure 1 A photograph of the carbon fiber electrode fabricated according to the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the process of preparing a carbon fiber-based tartaric acid molecularly imprinted electrochemical sensor according to the present invention.

[0020] Figure 3The image shows the SEM morphology of the molecularly imprinted polymer-modified carbon fiber electrode from Example 1.

[0021] Figure 4 The current response linearity graph of tartaric acid under different concentration conditions in Example 1 is shown, where the concentrations of tartaric acid are 5 μM, 10 μM, 50 μM, 200 μM, 300 μM, 400 μM, 500 μM, and 600 μM. Detailed Implementation

[0022] Example 1

[0023] A molecularly imprinted polymer (MIM) modified carbon fiber electrode is first prepared by ultrasonically cleaning hydrophilic carbon cloth with ethanol and then with a mixture of ethanol and water, followed by drying at 50°C. Carbon filaments approximately 5 × 10 mm in length are extracted from the cleaned carbon cloth, one end is wrapped with copper foil, and then dried for later use. Subsequently, a tartaric acid MIM layer is formed on the surface of the carbon fiber substrate through electrochemical polymerization. The MIM layer uses o-phenylenediamine as the functional monomer and tartaric acid as the template molecule.

[0024] Application Example 1

[0025] A method for preparing and applying a molecularly imprinted polymer-modified carbon fiber electrode in the detection of tartaric acid includes the following steps:

[0026] (1) The hydrophilic carbon cloth was pretreated by ultrasonic cleaning with ethanol and water and then dried at 50°C. Carbon filaments approximately 5×10 mm in length were extracted from the cleaned carbon cloth, one end was wrapped with copper foil, and then dried for later use. The resulting carbon fiber electrode is shown in the image below. Figure 1 As shown. The prepared carbon fiber electrode was subjected to 0.5 mol / L... -1 Electrochemical activation was performed by continuously scanning within a potential range of -0.5 to +1.5 V in H2SO4 solution until a stable cyclic voltammetry curve was obtained.

[0027] (2) Acetate buffer (pH=5) was used as the solvent, and tartaric acid (2mM) and o-phenylenediamine (3mM) were used as the template molecule and functional monomer, respectively. The carbon fiber electrode was immersed in the above polymerization solution. Cyclic voltammetry was used to perform 30 cycles of electropolymerization between 0 and +0.8V to form a molecularly imprinted polymer film on the surface of the carbon fiber electrode. The carbon fiber electrode was then eluted in an ethanol-water solution (ethanol / water = 2:1) for 3 min to remove the template molecules, thus obtaining the molecularly imprinted polymer-modified carbon fiber electrode.

[0028] First, a standard curve for tartaric acid detection was established (using PBS electrolyte with a pH of 3.5-6.5): The eluted carbon fiber electrode was placed in 10 mL of tartaric acid solutions of different concentrations for 3 min for specific adsorption. Then, the carbon fiber electrode was placed in a 5 mM potassium ferricyanide solution using a traditional three-electrode system. Differential pulse voltammetry was employed to detect the current signal within a voltage range of -0.5 to +0.6 V, thus establishing a standard curve for tartaric acid detection based on tartaric acid concentration versus current signal intensity. Figure 4 As shown, the concentration range of tartaric acid is 5-600 μM. The current signal of the carbon fiber electrode decreases with increasing tartaric acid concentration, and the linear relationship is I = 0.1157C. 酒石酸 +12.842, R 2 =0.9944, detection limit is 0.05 μmol / L, linear range is 1-800 μmol / L. For example... Figure 4 As shown.

[0029] Example 2

[0030] A method for preparing and applying a molecularly imprinted polymer-modified carbon fiber electrode in the detection of tartaric acid includes the following steps:

[0031] (1) The hydrophilic carbon cloth was pretreated by ultrasonic cleaning with ethanol and water and then dried at 50°C. Carbon filaments approximately 5×10 mm in length were extracted from the cleaned carbon cloth, one end was wrapped with copper foil, and then dried for later use. The resulting carbon fiber electrode is shown in the image below. Figure 1 As shown. The prepared carbon fiber electrode was subjected to 0.5 mol / L... -1 Electrochemical activation was performed by continuously scanning within a potential range of -0.5 to +1.5 V in H2SO4 solution until a stable cyclic voltammetry curve was obtained.

[0032] (2) Acetate buffer (pH = 5.2) was used as the solvent, and tartaric acid (2 mM) and o-phenylenediamine (5 mM) were used as the template molecule and functional monomer, respectively. The carbon fiber electrode was immersed in the above polymerization solution. Cyclic voltammetry was used to perform 30 cycles of electropolymerization between 0 and +0.8 V to form a molecularly imprinted polymer film on the surface of the carbon fiber electrode. Then, the carbon fiber electrode was eluted in an ethanol-water solution (ethanol / water = 2:1) for 5 min to remove the template molecules, thus obtaining the molecularly imprinted polymer-modified carbon fiber electrode.

[0033] Application Example 2

[0034] A method for preparing a molecularly imprinted polymer-modified carbon fiber electrode for the detection of tartaric acid and its application in real samples includes the following steps:

[0035] (1) The hydrophilic carbon cloth was pretreated by ultrasonic cleaning with ethanol and water and then dried at 50°C. Carbon filaments approximately 5×10 mm in length were extracted from the cleaned carbon cloth, one end was wrapped with copper foil, and then dried for later use. The resulting carbon fiber electrode is shown in the image below. Figure 1 As shown. The prepared carbon fiber electrode was subjected to 0.5 mol / L... -1 Electrochemical activation was performed by continuously scanning within a potential range of -0.5 to +1.5 V in H2SO4 solution until a stable cyclic voltammetry curve was obtained.

[0036] (2) Acetate buffer (pH = 5.2) was used as the solvent, and tartaric acid (2 mM) and o-phenylenediamine (5 mM) were used as the template molecule and functional monomer, respectively. The carbon fiber electrode was immersed in the above polymerization solution. Cyclic voltammetry was used to perform 30 cycles of electropolymerization between 0 and +0.8 V to form a molecularly imprinted polymer film on the surface of the carbon fiber electrode. Then, the carbon fiber electrode was eluted in an ethanol-water solution (ethanol / water = 2:1) for 5 min to remove the template molecules, thus obtaining the molecularly imprinted polymer-modified carbon fiber electrode.

[0037] The standard addition method is used to determine the concentration of tartaric acid in wine samples. This method involves adding a target substance of known concentration to the sample. Sample preparation method: Wine samples are filtered using a 0.45 μm pore size filter membrane. The sample is then added to 0.1 mol / L... -1 The sample was diluted 157-fold in PBS (pH 6) for the detection of tartaric acid. The recovery experiment followed the same procedure, adding a known amount of standard tartaric acid to the sample. The samples were measured using differential pulse voltammetry (DPV), and the results are shown in Table 1.

[0038] Table 1

[0039]

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A molecularly imprinted polymer-modified carbon fiber electrode, characterized in that: It includes a carbon fiber substrate and a tartaric acid molecularly imprinted polymer layer formed on the surface of the carbon fiber substrate through electrochemical polymerization.

2. The molecularly imprinted polymer-modified carbon fiber electrode as described in claim 1, characterized in that: The carbon fiber substrate undergoes ultrasonic cleaning pretreatment with ethanol and water.

3. The molecularly imprinted polymer-modified carbon fiber electrode as described in claim 1, characterized in that: The molecularly imprinted polymer layer is formed by electrochemical polymerization using o-phenylenediamine as a functional monomer and tartaric acid as a template molecule.

4. The molecularly imprinted polymer-modified carbon fiber electrode as described in claim 1, characterized in that, The specific steps are as follows: After ultrasonic cleaning and pretreatment with ethanol and water, the carbon fiber substrate is dried. Using acetate buffer as solvent, tartaric acid and o-phenylenediamine are used as template molecules and functional monomers, respectively. The treated carbon fiber substrate is immersed in the above polymerization solution. Cyclic voltammetry is used to carry out 30 cycles of electropolymerization between 0 and +0.8V to form a molecularly imprinted polymer film on the surface of the carbon fiber substrate. Then, the carbon fiber electrode is eluted in an ethanol aqueous solution to remove the template molecules, thus obtaining the carbon fiber electrode modified with molecularly imprinted polymer.

5. A method for applying the molecularly imprinted polymer-modified carbon fiber electrode as described in claim 1 in the detection of tartaric acid, characterized in that, The method includes the following: the prepared carbon fiber electrode is placed in a potassium ferricyanide solution for detection, and the characteristic oxidation peak of tartaric acid is detected by differential pulse voltammetry in the potential range of -0.5 to +0.6 V (vs. Ag / AgCl) to achieve quantitative analysis.

6. The method for applying a molecularly imprinted polymer-modified carbon fiber electrode to the detection of tartaric acid as described in claim 5, characterized in that: Using 0.1M PBS as the electrolyte, the detection limit was 0.05 μmol / L, and the linear range was 1–800 μmol / L.

7. The method for applying a molecularly imprinted polymer-modified carbon fiber electrode to the detection of tartaric acid as described in claim 6, characterized in that: The electrolyte has a pH of 3.5-6.

5.

8. The molecularly imprinted polymer-modified carbon fiber electrode as described in any one of claims 1-4 is applied to a rapid detection system for tartaric acid in wine.

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